High Temperature Oxidation and Chlorination of FeCrAl alloys
Doctoral thesis, 2014

Abstract The constant strive for improved efficiency and lower-cost industrial processes often results in progressively higher temperatures and more aggressive environments. High- temperature corrosion is a well-known problem in biomass- and waste-fired boilers and is one of the obstacles to overcome in achieving a more sustainable society. Alkali- and chlorine- induced corrosion of chromia-forming alloys has been studied by several researchers. However, the literature is scarce on how alumina forming-alloys, e.g. FeCrAl alloys, perform in such an aggressive environment. In this thesis, the KCl-induced corrosion of FeCrAl alloys is studied through well-planned laboratory exposures, detailed analyses and corrosion tests in a full scale waste-fired power boiler. In the laboratory, the effect of adding small amounts of KCl was investigated on polished FeCrAl samples in O2 or O2 + H2O environments up to 168 hours at 600 °C. Pre-formed alumina scales were prepared on the alloy substrate through pre-oxidation at various conditions. The pre-treated samples were subsequently exposed to O2 + H2O + KCl in order to investigate their corrosion resistance. The samples were analysed using TGA, SEM/EDX, XRD, IC, AES, SIMS, BIB cross sections and STEM/EDX. In order to evaluate the validity of the findings in the laboratory studies, corrosion tests were carried out in a full-scale combined heat and power (CHP) boiler. The study showed that KCl-induced corrosion caused a rapidly growing iron-chromium-rich oxide to form in O2 and O2 + H2O environments at 600 °C. Chromate formation and alloy chlorination were found to initiate the formation of a non-protective oxide scale. Alloy chlorination was greater in O2 than in O2 + H2O resulting in a more porous scale with poor adhesion to the alloy substrate. Pre-treating the alloy prior to exposure to O2 + H2O + KCl mitigated the corrosion, since alumina, itself, is rather inert towards corrosion. However, the corrosion started locally, most likely at flaws/cracks in the alumina scale and then spread laterally until the entire surface suffered from breakaway corrosion. Similar results were obtained in the corrosion tests in the waste-fired boiler. The pre-formed alumina scale failed after only 24 hours in the boiler at both 600 and 700 °C.





high-temperature corrosion


HA3-salen, Hörsalsvägen 4, Chalmers
Opponent: Professor John Nicholls, Cranfield University, UK.


Niklas Israelsson

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Areas of Advance


Materials Science

Subject Categories

Metallurgy and Metallic Materials



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie

HA3-salen, Hörsalsvägen 4, Chalmers

Opponent: Professor John Nicholls, Cranfield University, UK.

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